We’ve used Siri to get directions, to make hands-free mobile calls and to fetch answers to trivia questions. Sometimes we just goof on Siri. “Siri, do you love me?” my daughter asked the other day. (Siri’s heartbreaking response: “I am not capable of love.”) Most ways you look at it, Siri is pretty magical.

But not in every way. Siri’s dirty little secret is that she’s a bandwidth guzzler, the digital equivalent of a 10-miles-per-gallon Hummer H1.

To make your wish her command, Siri floods your cell network with a stream of data; her responses require a similarly large flow in return. A study published this month by Arieso, an Atlanta firm that specializes in mobile networks, found that the Siri-equipped iPhone 4S uses twice as much data as does the plain old iPhone 4 and nearly three times as much as does the iPhone 3G. The new phone requires far more data than most other advanced smartphones, which are pretty data-intensive themselves, The Post has reported.

In all, Arieso says that the Siri-equipped iPhone 4S “appears to unleash data consumption behaviors that have no precedent.”